Problems have been encountered in the sealing of tubular members, such as a blowout preventer, a production tree or a side outlet valve, to a wellhead housing during drilling and subsequently upon completion of the well. Typically, metal gaskets or sealing rings have been used which provide tapered surfaces on the exterior of the ring for sealing against tapered surfaces of the joint members. Such tapered sealing surfaces normally require at least a slight coining between the ring and the sealing surfaces of the joint members for proper sealing between the two joint members.
When seating on cylindrical sealing surfaces has been attempted, often the surfaces have been damaged during the drilling operations and this prevents an effective seal when the production tree is later installed on the wellhead housing.
U.S. Pat. No. 4,214,763 discloses a seal for use between the tapered surfaces in recesses of abutting tubular members and includes a seal ring having an inner bore, end surfaces, tapered sealing surfaces extending outwardly and converging toward each other from the outer portion of the end surfaces and a relieved area intermediate said sealing surfaces with a tapered alignment surface midway between the end surfaces.
U.S. Pat. No. 4,471,965 discloses in FIG. 3 a sealing element which includes a ring having a central bore, and outer sealing projections at each end of the ring adapted to engage the sealing surfaces of the recess defined in the inner ends of the abutting tubular members. FIG. 2 of this references illustrates another type of seal which includes a ring which projects within the bores of the abutting tubular members being connected and includes upper and lower outer sealing projections which are to seal against the interior of the tubular members and a central outer projections which is to be clamped between the facing surfaces of the tubular members.
U.S. Pat. No. 4,766,956 discloses an annular seal having rims which have outer lips which are curved to present a curved convex surface for sealing against the sealing surfaces to be engaged.
A sealing ring for sealing against cylindrical sealing surfaces is disclosed in the copending application of Timothy C. Davies, U.S. Ser. No. 07/189,027, filed May 2, 1988 now abandoned. The sealing ring of such application includes lips extending along the cylindrical surface and having an annular bulge near the outer ends of the lips with a relatively short flat sealing surface thereon for engaging the cylindrical sealing surface. The lip further includes an enlarged section between the root of the lip and the lip sealing surface.
Another replacement type of sealing ring disclosed in the pending U.S. application for patent of W. M. Taylor et al, Ser. No. 07/106,663, now abandoned, includes a seal body having external tapers together with a rim extending axially from the end of one of the tapers which is adapted to be press fitted into a recess to seal against the wall of the recess below a damaged tapered surface on the interior end of one of the tubular members.